TSB on my 99 jimmy

hi, I have a problem, well I looked up the TSBs on my jimmy and I found one that said somthing about the fuel injector staying closed and not working, well when I called the dealer in town they said it has no recalls on it, but the funny thing is I DO have a non functional fuel injector on cylinder 4. (cylinder #4 misfire code) So does that mean they have replaced it already and it went bad again or does it mean that it went bad for the first time.